U.S. patent application number 12/149463 was filed with the patent office on 2008-11-13 for optical connector and method for assembling optical connector.
Invention is credited to Junji Fukui, Wataru Sakurai, Mitsuaki Tamura.
Application Number | 20080279508 12/149463 |
Document ID | / |
Family ID | 39687067 |
Filed Date | 2008-11-13 |
United States Patent
Application |
20080279508 |
Kind Code |
A1 |
Fukui; Junji ; et
al. |
November 13, 2008 |
Optical connector and method for assembling optical connector
Abstract
To provide an optical connector that enables the reduction in
the number of parts and can be easily attached to an optical cable,
a concave portion 18 for a ferrule is formed in a plug housing 6,
and a ferrule 3 is inserted from the side of a collar portion 10
into the concave portion 18 for a ferrule. A hook portion 28 for a
ferrule is provided in a protruding condition inside the plug
housing 6. The collar portion 10 is guided by the hook portion 28
for a ferrule, which has been elastically deformed, and moves
toward a bottom surface 26 of the concave portion 18 for a ferrule.
Where the collar portion 10 reaches a space between the bottom
surface 26 and the hook portion 28 for a ferrule, the hook portion
28 for a ferrule is elastically restored. Therefore, even if the
collar portion 10 tries to move toward an opening 24 of the concave
portion 18 for a ferrule, the collar portion is locked by the hook
portion 28 for a ferrule and the movement is inhibited. Thus, in
the plug-type optical connector 1, the ferrule 3 can be positioned
by inserting into the plug housing 6 and moving.
Inventors: |
Fukui; Junji; (Yokohama-shi,
JP) ; Sakurai; Wataru; (Yokohama-shi, JP) ;
Tamura; Mitsuaki; (Yokohama-shi, JP) |
Correspondence
Address: |
MCDERMOTT WILL & EMERY LLP
600 13TH STREET, N.W.
WASHINGTON
DC
20005-3096
US
|
Family ID: |
39687067 |
Appl. No.: |
12/149463 |
Filed: |
May 1, 2008 |
Current U.S.
Class: |
385/72 |
Current CPC
Class: |
G02B 6/3882 20130101;
G02B 6/3893 20130101; G02B 6/3869 20130101; G02B 6/3885 20130101;
G02B 6/3821 20130101 |
Class at
Publication: |
385/72 |
International
Class: |
G02B 6/38 20060101
G02B006/38 |
Foreign Application Data
Date |
Code |
Application Number |
May 2, 2007 |
JP |
P2007-121772 |
Claims
1. An optical connector that is attached to an optical cable in
which an optical fiber is covered with a cable sheath, the optical
connector comprising: a ferrule that holds a distal end portion of
the optical fiber exposed from the cable sheath; and a housing
having in one end portion thereof a concave portion for a ferrule,
which serves to accommodate the ferrule, wherein the ferrule has a
body portion and a collar portion formed at one end side of the
body portion and is introduced into the concave portion for a
ferrule from the collar portion side, and a hook portion for a
ferrule, which can be elastically deformed, is provided in a
protruding condition at an inner wall surface extending between an
opening and a bottom surface of the concave portion for a ferrule
in the housing, and the hook portion for a ferrule is elastically
deformed and guides the collar portion toward a bottom surface side
of the concave portion for a ferrule when the ferrule is introduced
into the concave portion for a ferrule, and is elastically restored
and locks the collar portion when the collar portion reaches a
space between the hook portion for a ferrule and the bottom surface
of the concave portion for a ferrule.
2. The optical connector according to claim 1, further comprising a
guide pin for positioning, which has a groove formed in an outer
peripheral surface of one end portion thereof, wherein the guide
pin is inserted into the body portion and the collar portion of the
ferrule, and the one end portion of the guide pin protrudes from an
end surface of the collar portion, the housing further has a
concave portion for a pin, which is open at the bottom surface of
the concave portion for a ferrule and serves to accommodate the one
end portion of the guide pin, and a hook portion for a pin is
provided in a protruding condition in an open portion of the
concave portion for a pin, and the hook portion for a pin is
elastically deformed and guides the one end portion of the guide
pin into the concave portion for a pin when one end portion of the
guide pin is introduced into the concave portion for a pin, and is
elastically restored and locks the groove of the guide pin when the
groove of the guide pin reaches a position corresponding to the
hook portion for a pin.
3. The optical connector according to claim 1, wherein the housing
further has a concave portion for an elastic member, which is open
at the bottom surface of the concave portion for a ferrule and
accommodates the elastic member, and the elastic member
accommodated in the concave portion for an elastic member biases
the collar portion of the ferrule accommodated between the hook
portion for a ferrule and the bottom surface of the concave portion
for a ferrule toward the hook portion for a ferrule.
4. The optical connector according to claim 1, wherein a cable
insertion hole for inserting the optical cable is provided between
the bottom surface of the concave portion for a ferrule and the
other end of the housing in the housing, and there is further
provided a cable fixing member that fixes a position of the optical
cable inserted into the cable insertion hole by caulking from
outside.
5. A method for assembling an optical connector, comprising the
steps of: preparing a ferrule comprising a body portion and a
collar portion formed at one end side of the body portion;
preparing a housing comprising a concave portion for a ferrule,
which serves to accommodate the ferrule, at one end side and
provided with locking means for locking the ferrule; inserting one
end portion of an optical cable into the housing; inserting an
optical fiber exposed by removing a cable sheath at one end portion
of the optical cable into the ferrule and fixing; and introducing
the ferrule from the collar portion side into the concave portion
for a ferrule of the housing and locking the collar portion with
the locking means.
Description
BACKGROUND OF THE INVENTION
[0001] 1. Field of the Invention
[0002] The present invention relates to an optical connector that
can be used when abutting and connecting optical fibers exposed
from optical cables, and to a method for assembling the optical
connector.
[0003] 2. Related Background Art
[0004] A conventional optical connector is known that comprises,
for example as described in Patent Document 1, a ferrule having a
body portion (cylindrical body) and a collar portion (collar
member), a stop ring that holds a rear end portion of the collar
portion, a plug frame that holds a distal end portion of the collar
portion, and a housing (plug housing) that covers the plug frame.
In the conventional optical connector, the ferrule is positioned
inside the optical connector by sandwiching the collar portion
between the stop ring and the plug frame. [Patent Document 1]
Japanese Patent Application Laid-open No. 11-305075.
SUMMARY OF THE INVENTION
[0005] However, in the conventional optical connector, a plurality
of parts, namely, the stop ring and plug frame, are required to
position the ferrule. The resultant problem is that the production
cost rises. Furthermore, because these parts are small, they are
very difficult to assemble.
[0006] Accordingly, it is an object of the present invention to
provide an optical connector that enables the reduction in the
number of parts and can be easily attached to an optical cable.
[Means for Resolving the Problem]
[0007] The optical connector in accordance with the present
invention is an optical connector that is attached to an optical
cable in which an optical fiber is covered with a cable sheath,
comprising: a ferrule that holds a distal end portion of the
optical fiber exposed from the cable sheath; and a housing having
in one end portion thereof a concave portion for a ferrule, which
serves to accommodate the ferrule, wherein the ferrule has a body
portion and a collar portion formed at one end side of the body
portion and is introduced into the concave portion for a ferrule
from the collar portion side, and a hook portion for a ferrule,
which can be elastically deformed, is provided in a protruding
condition at an inner wall surface extending between an opening and
a bottom surface of the concave portion for a ferrule in the
housing, and the hook portion for a ferrule is elastically deformed
and guides the collar portion toward the bottom surface side of the
concave portion for a ferrule when the ferrule is introduced into
the concave portion for a ferrule, and is elastically restored and
locks the collar portion when the collar portion reaches a space
between the hook portion for a ferrule and the bottom surface of
the concave portion for a ferrule.
[0008] In the optical connector in accordance with the present
invention, the concave portion for a ferrule is formed in the
housing, and the ferrule is inserted from the side of the collar
portion into the concave portion for a ferrule. The hook portion
for a ferrule is provided in a protruding condition inside the
concave portion for a ferrule. The collar portion of the ferrule
inserted into the concave portion for a ferrule is guided by the
hook portion for a ferrule, which has been elastically deformed,
and moves toward the bottom surface side of the concave portion for
a ferrule. Where the collar portion reaches a space between the
bottom surface of the concave portion for a ferrule and the hook
portion for a ferrule, the hook portion for a ferrule is
elastically restored. Therefore, even if the collar portion tries
to move toward the opening of the concave portion for a ferrule,
the collar portion is locked by the elastically restored hook
portion for a ferrule and the movement is inhibited. As a result,
the collar portion of the ferrule is positioned between the bottom
surface of the concave portion for a ferrule and the hook portion
for a ferrule. Thus, in accordance with the present invention, the
ferrule can be positioned by inserting into the housing and moving.
Therefore, no parts have to be prepared separately for positioning
the ferrule and the operation of attaching to the optical cable can
be easily performed.
[0009] Preferably, a guide pin for positioning that has a groove
formed in an outer peripheral surface of one end portion thereof is
further provided, the guide pin is inserted into the body portion
and the collar portion of the ferrule, the one end portion of the
guide pin protrudes from an end surface of the collar portion, the
housing further has a concave portion for a pin, which is open at
the bottom surface of the concave portion for a ferrule and serves
to accommodate the one end portion of the guide pin, a hook portion
for a pin is provided in a protruding condition in an open portion
of the concave portion for a pin, and the hook portion for a pin is
elastically deformed and guides the one end portion of the guide
pin into the concave portion for a pin when one end portion of the
guide pin is introduced into the concave portion for a pin, and is
elastically restored and locks the groove of the guide pin when the
groove of the guide pin reaches a position corresponding to the
hook portion for a pin.
[0010] In the optical connector in accordance with the present
invention, the concave portion for a pin is formed in the housing,
and a hook portion for a pin is provided in the open portion of
this concave portion for a pin. Because the hook portion for a pin
guides one end portion of the guide pin into the concave portion
for a pin, the one end of the guide pin is easily introduced into
the concave portion for a pin. Where the groove of the guide pin
reaches a position corresponding to the hook portion for a pin, the
hook portion for a pin locks the groove, thereby holding the one
end portion of the guide pin. Thus, in accordance with the present
invention, the guide pin can be fixed to the housing by inserting
into the concave portion for a pin.
[0011] The method for assembling an optical connector in accordance
with the present invention comprises the steps of: preparing a
ferrule comprising a body portion and a collar portion formed at
one end side of the body portion; preparing a housing comprising a
concave portion for a ferrule, which serves to accommodate the
ferrule at one end side and provided with locking means for locking
the ferrule; inserting one end portion of an optical cable into the
housing; inserting an optical fiber exposed by removing a cable
sheath at one end portion of the optical cable into the ferrule and
fixing; and introducing the ferrule from the collar portion side
into the concave portion for a ferrule of the housing and locking
the collar portion with the locking means.
[0012] With the method for assembling an optical connector in
accordance with the present invention, the ferrule holding the end
portion of the optical fiber is introduced into the concave portion
for a ferrule of the housing and the collar portion of the ferrule
is locked by the locking means of the housing, whereby the ferrule
is positioned with respect to the housing. Therefore, no parts have
to be prepared separately for positioning the ferrule and the
operation of attaching to the optical cable can be easily
performed.
[0013] Preferably, a cable insertion hole for inserting the optical
cable is provided between the bottom surface of the concave portion
for a ferrule and the other end of the housing in the housing, and
there is further provided a cable fixing member that fixes the
position of the optical cable inserted into the cable insertion
hole by caulking from outside.
[0014] In this case, because, the optical cable extending from the
ferrule is also positioned and fixed, the ferrule can be positioned
with even better reliability.
[0015] Preferably, the housing is composed of a PBT resin. Further,
it is preferred that the housing be composed of a material having
heat resistance, rigidity, electric properties, and moldability
similar to those of the PBT resin. In this case, the housing excels
in heat resistance, rigidity, electric properties, and moldability
and is, therefore, optimum for long-term use.
[Effect of the Invention]
[0016] The present invention can provide an optical connector that
enables the reduction in the number of parts and can be easily
attached to an optical cable. Therefore, the production cost can be
reduced and the attachment to the optical cable can be performed
smoothly.
BRIEF DESCRIPTION OF THE DRAWINGS
[0017] FIG. 1 is a perspective view illustrating a plug-type
optical connector of the first embodiment and a socket type optical
connector of the second embodiment.
[0018] FIG. 2 is a cross-sectional view in the horizontal direction
of the plug-type optical connector of the first embodiment, this
figure serving to explain a process of attaching to an optical
cable.
[0019] FIG. 3 is a cross-sectional view in the vertical direction
of the plug-type optical connector of the first embodiment.
[0020] FIG. 4 is a cross-sectional view in the horizontal direction
of the socket-type optical connector of the second embodiment.
[0021] FIG. 5 is a cross-sectional view in the horizontal direction
illustrating the connected state of the plug-type optical connector
of the first embodiment and the socket-type optical connector of
the second embodiment.
DESCRIPTION OF THE PREFERRED EMBODIMENTS
[0022] The preferred embodiments of the present invention will be
described below in greater details with reference to the appended
drawings. In the explanation below, identical elements or elements
having identical functions will be assigned with identical
reference symbols and redundant explanation thereof will be
omitted.
[0023] FIG. 1 is a perspective view illustrating a plug-type
optical connector of the first embodiment and a socket type optical
connector of the second embodiment. FIG. 2 is a cross-sectional
view in the horizontal direction of the plug-type optical connector
of the first embodiment, this figure serving to explain a process
of attaching to an optical cable. FIG. 3 is a cross-sectional view
in the vertical direction of the plug-type optical connector of the
first embodiment. FIG. 4 is a cross-sectional view in the
horizontal direction of the socket-type optical connector of the
second embodiment. FIG. 5 is a cross-sectional view in the
horizontal direction illustrating the connected state of the
plug-type optical connector of the first embodiment and the
socket-type optical connector of the second embodiment. Further,
the plug-type optical connector of the first embodiment will be
explained, and then the socket-type optical connector of the second
embodiment will be explained.
[0024] As shown in FIG. 1, the plug-type optical connector 1 of the
first embodiment is an optical connector that will be attached to
an optical cable 2 in which an optical fiber 2a is covered with a
cable sheath. The plug-type optical connector 1, as shown in FIG.
2, comprises a ferrule 3, a compression coil spring (elastic
member) 5, and a plug housing (housing) 6.
[0025] The ferrule 3 serves to hold a distal end portion of the
optical fiber 2a. More specifically, it is an MT connector ferrule.
The ferrule 3 has a body portion 8 and a collar portion 10 formed
integrally with one end side of the body portion 8. Because the
collar portion 10 protrudes from the body portion 8, a step is
configured between the collar portion 10 and body portion 8.
[0026] Through optical fiber insertion holes (not shown in the
figures) for inserting the optical fiber 2a are formed in the body
portion 8 and collar portion 10. The optical fiber insertion hole
is opened in a distal end surface 8a of the body portion 8 and a
rear end surface 10a of the collar portion 10. Further, a pair of
guide pin insertion holes 14 are formed in the body portion 8. The
guide pin insertion holes 14 are positioned on both sides of the
optical fiber insertion hole and opened in the distal end surface
8a of the body portion 8. As shown in FIG. 5, guide pins 54 for
alignment are inserted in respective guide pin insertion holes
14.
[0027] An open portion 12 is formed in the upper wall portion of
the body portion 8. The open portion 12 is positioned directly
above the optical fiber insertion hole, and the optical fiber 2a
inserted into the optical fiber insertion hole can be fixed to the
ferrule 3 by pouring an adhesive from the open portion 12.
[0028] The ferrule 3 having the above-described configuration is
accommodated in the plug housing 6 as shown in (c) of FIG. 2. The
plug housing 6 has a concave portion 18 for a ferrule, which serves
to accommodate the ferrule 3 and a concave portion 20 for a spring
(concave portion for an elastic member) for accommodating the
compression coil spring 5 between one end 6a and another end
6b.
[0029] The concave portion 18 for a ferrule is formed in one end
portion of the plug housing 6. The concave portion 18 for a ferrule
is opened at one end surface of the plug housing 6, and a plurality
(two in the present embodiment) of hook portions 28 (locking means)
for a ferrule are provided in a protruding condition at the inner
wall surface extending between an opening 24 and a bottom surface
26 of the concave portion 18 for a ferrule.
[0030] A hook portion 28 for a ferrule has a guide surface 28a for
guiding the ferrule 3 toward the bottom surface 26 of the concave
portion 18 for a ferrule and a locking surface 28b for locking the
ferrule 3 and can be elastically deformed in the width direction of
the plug housing 6. The guide surface 28a is so inclined as to
withdraw from the base of the hook portion 28 for a ferrule as the
bottom surface 26 (left side in FIG. 2) of the concave portion 18
for a ferrule is approached. The locking surface 28b faces the
bottom surface 26 of the concave portion 18 for a ferrule and is
almost perpendicular to the installation surface of the hook
portion 28 for a ferrule.
[0031] The concave portion 20 for a spring is formed between the
concave portion 18 for a ferrule and the other end 6b of the plug
housing 6 and opened at the bottom surface 26 of the concave
portion 18 for a ferrule. The length from the opening 30 of the
concave portion 20 for a spring to the bottom surface 32 of the
concave portion 20 for a spring is shorter than the natural length
of the compression coil spring 5. The compression coil spring 5
disposed in the concave portion 20 for a spring is abutted by one
end thereof against the rear end surface 10a of the collar portion
10 of the ferrule 3 and abutted by the other end against the bottom
surface 32 of the concave portion 20 for a spring.
[0032] A cable insertion hole 34 is formed between the concave
portion 20 for a spring and the other end 6b of the plug housing 6.
The cable insertion hole 34 serves to insert the optical cable 2 in
a linearly extending state thereof and is opened at the bottom
surface 32 of the concave portion 20 for a spring and at the other
end surface of the plug housing 6.
[0033] As shown in FIG. 1, an open portion 36 is formed in an upper
wall portion of the plug housing 6. The open portion 36 is
positioned directly above the cable insertion hole 34. As also
shown in FIG. 5, a cable fixing member 37 is fitted in this open
portion 36. The cable fixing member 37 is a member for fixing the
optical cable 2 and has a pair of leg portions 38 provided with a
sharp edge (not shown in the figure). Where such cable fixing
member 37 is inserted from the open portion 36 and the sharp edges
of the leg portions 38 of the cable fixing member 37 penetrate into
the cable sheath of the optical cable 2, the optical cable 2 can be
fixed to the plug housing 6.
[0034] As shown in FIG. 1, a latch portion 40 that maintains a
joined state of the plug housing 6 and the below-described socket
housing 56 is provided integrally with the upper wall portion of
the plug housing 6. The latch portion 40 includes a latch arm 42
extending from one end 6a of the plug housing 6 to the other end
6b. One end of the latch arm 42 is fixed in the vicinity of one end
6a of the plug housing 6. Further, the latch arm 42 can be deformed
elastically in the direction crossing the plug housing 6. A locking
hook 44 that engages with the socket housing 56 is provided in a
protruding condition at the outer surface of the latch arm 42, that
is, at the surface facing the plug housing 6. Further, a knob 46
for releasing the engagement of the locking hook 44 with the socket
housing 56 is provided at the other end of the latch arm 42.
[0035] The plug housing 6 having the above-described configuration
is composed of a PBT resin. Where the PBT resin is used, the plug
housing 6 excels in heat resistance, rigidity, electric properties,
and moldability and is, therefore, optimum for long-term use. The
material of the plug housing 6 is not limited to a PBT resin, and
any material having heat resistance, rigidity, electric properties,
and moldability similar to those of the PBT resin may be used.
Examples of such materials include polyetherimides and
polyamidoimides.
[0036] A method for attaching the plug-type optical connector 1 to
the optical cable 2 will be explained below with reference to FIG.
2. First, the optical cable 2, ferrule 3, compression coil spring
5, and plug housing 6 are prepared. One end portion of the prepared
optical cable 2 is introduced in the cable insertion hole 34 of the
plug housing 6 and guided out from the opening 24 formed in one end
6a of the plug housing 6 via the cable insertion hole 34, concave
portion 20 for a spring, and concave portion 18 for a ferrule. The
compression coil spring 5 is fit onto a portion of the optical
cable 2 that has been taken out from the opening 24.
[0037] Then, the cable sheath at one end portion of the optical
cable 2 is removed and the optical fiber 2a is exposed. The exposed
optical fiber 2a is inserted into an optical fiber insertion hole
(not shown in the figure) of the ferrule 3. The optical fiber 2a is
introduced from the rear end surface 10a of the collar portion 10.
After the optical fiber 2a has been inserted, an adhesive is poured
from the open portion 12 of the ferrule 3 and the optical fiber 2a
is fixed to the ferrule 3. In this state, the ferrule 3 is not
connected to the plug housing 6, and the plug housing 6 can move
along the optical cable 2.
[0038] A jig 48 is then prepared. The jig 48 serves to push the
ferrule 3 into the plug housing 6 and has a pair of protruding
portions 49. The protruding portions 49 will be fitted into the
pair of guide pin insertion holes 14 formed in the ferrule 3 and
have a diameter and length enabling the insertion into the guide
pin insertion holes 14. In the ferrule 3, an optical fiber
insertion hole is provided between the guide pin insertion hole 14
and the guide pin insertion hole 14, and the end surface of the
optical fiber 2a inserted into the optical fiber insertion hole is
exposed from the distal end surface 8a of the body portion 8. The
zone between the protruding portion 49 and the protruding portion
49 of the jig 48 has a concave shape and prevents the jig 48 from
coming into contact with the end surface of the optical fiber 2a
exposed from the distal end surface 8a.
[0039] As shown in (a) of FIG. 2, the protruding portions 49 of the
prepared jig 48 are inserted into the guide pin insertion holes 14
of the ferrule 3. Upon insertion, the plug housing 6 is moved in
the direction of arrow A, that is, in the direction for approaching
the jig 48. As the plug housing 6 moves, the ferrule 3 is
introduced from the side of the collar portion 10 into the concave
portion 18 for a ferrule of the plug housing 6.
[0040] The ferrule 3 introduced into the concave portion 18 for a
ferrule is moved in relation to the bottom surface 26 of the
concave portion 18 for a ferrule by the movement of the plug
housing 6. As a result, the collar portion 10 of the ferrule 3 is
abutted against the guiding surfaces 28a of two hook portions 28
for a ferrule. Upon the abutment, as the plug housing 6 moves
further, the inclined guiding surface 28a is pushed by the collar
portion 10 and the hook portion 28 for a ferrule is elastically
deformed. As a result, the space between the guiding surface 28a of
one hook portion 28 for a ferrule and guiding surface 28a of
another hook portion 28 for a ferrule is expanded by the collar
portion 10. As the plug housing 6 moves, the collar portion 10
moves toward the bottom surface 26 of the concave portion 18 for a
ferrule, while expanding the space between the guiding surface 28a
and the guiding surface 28a. At this time, the inclined guiding
surface 28a serves to guide the collar portion 10 toward the bottom
surface 26.
[0041] Where the collar portion 10 reaches the space between the
bottom surface 26 of the concave portion 18 for a ferrule and the
hook portion 28 for a ferrule, following the subsequent movement of
the plug housing 6, the guiding surface 28a is released from the
push-down state. As a result, the hook portion 28 for a ferrule is
elastically restored. As shown in (b) of FIG. 2, once the hook
portion 28 for a ferrule is elastically restored, the movement of
the plug housing 6 is stopped. At this time, the compression coil
spring 5 is accommodated in the concave portion 20 for a
spring.
[0042] After the movement of the plug housing 6 has been stopped,
as shown in (c) of FIG. 2, the jig 48 is moved in the direction of
arrow B, that is, in the direction of withdrawing from the plug
housing 6, and the protruding portions 49 are pulled out from the
guide pin insertion holes 14. As a result, the pressure applied to
the ferrule 3 from the jig 48 is reduced. Instead, the ferrule 3 is
biased by the compression coil spring 5. As a result, the collar
portion 10 of the ferrule 3 is pushed toward the hook portion 28
for a ferrule and comes into contact with the locking surface 28b
of the hook portion 28 for a ferrule. The locking surface 28b stops
the collar portion 10, and the ferrule 3 biased by the compression
coil spring 5 is prevented from jumping out from the opening 24 of
the concave portion 18 for a ferrule.
[0043] After the jig 48 has been separated from the ferrule 3, the
cable fixing member 37 is inserted into the open portion 36 of the
plug housing 6, and the leg portions 38 of the cable fixing member
37 are caused to penetrate into the cable sheath of the optical
cable 2. The optical cable 2 is thus caulked from outside and
fixedly positioned, whereby the ferrule 3 can be more reliably
positioned inside the concave portion 18 for a ferrule.
[0044] As described hereinabove, in the plug-type optical connector
1 of the present embodiment, the concave portion 18 for a ferrule
is formed in the plug housing 6, and the ferrule 3 is inserted from
the side of the collar portion 10 into the concave portion 18 for a
ferrule. The hook portion 28 for a ferrule is provided in a
protruding condition inside the concave portion 18 for a ferrule,
and the collar portion 10 inserted into the concave portion 18 for
a ferrule is guided by the hook portion 28 for a ferrule, which has
been elastically deformed and moves toward the bottom surface 26 of
the concave portion 18 for a ferrule. Where the collar portion 10
reaches the space between the bottom portion 26 of the concave
portion 18 for a ferrule and the hook portion 28 for a ferrule, the
hook portion 28 for a ferrule is elastically restored. As a result,
even if the collar portion 10 of the ferrule 3 moves toward the
opening 24 of the concave portion 18 for a ferrule, it is locked by
the elastically restored hook portion 28 for a ferrule and the
movement thereof is inhibited. Thus, in the plug-type optical
connector 1 of the present embodiment, the ferrule 3 can be
positioned by inserting into the concave portion 18 for a ferrule
located inside the plug housing 6 and moving toward the bottom
surface 26. As a result, no parts have to be prepared separately
for positioning the ferrule 3 and the operation of attaching to the
optical cable 2 can be easily performed.
[0045] Further, in the plug-type optical connector 1 of the present
embodiment, the compression coil spring 5 accommodated in the
concave portion 20 for a spring biases the collar portion 10 of the
ferrule 3 accommodated between the bottom surface 26 of the concave
portion 18 for a ferrule and the hook portion 28 for a ferrule
toward the hook portion 28 for a ferrule. By pushing the collar
portion 10 against the hook portion 28 for a ferrule, it is
possible to fix reliably the position of the ferrule 3. However, by
contrast with a complete position fixing, a certain degree of
movement is allowed for the ferrule 3. As a result, when the
optical fiber 2a held in the ferrule 3 is connected to an optical
fiber held in another ferrule, stresses applied to the connection
portion can be reduced.
[0046] A socket-type optical connector of the second embodiment
will be described below.
[0047] As shown in FIG. 1, a socket-type optical connector 50 of
the present embodiment is an optical connector that will be
attached to an optical cable 52 in which an optical fiber 52a is
covered with a cable sheath. The socket-type optical connector 50,
as shown in FIG. 4, comprises a ferrule 53, a guide pin 54, a
compression coil spring (elastic member) 55, and a socket housing
(housing) 56.
[0048] The ferrule 53 serves to hold a distal end portion of the
optical fiber 52a and is a MT ferrule that is usually used. The
ferrule 53 has a configuration substantially identical to that of
the ferrule 3 in the plug-type optical connector 1 of the first
embodiment. A body portion 58 of the ferrule 53 is equivalent to
the body portion 8 of the ferrule 3, and a collar portion 60 of the
ferrule 53 is equivalent to the collar portion 10 of the ferrule
3.
[0049] A pair of guide pin insertion holes 64 are formed in the
ferrule 53. By contrast with the guide pin insertion holes 14 of
ferrule 3, the guide pin insertion holes 64 of the ferrule 53 are
formed through the body portion 58 and collar portion 60.
[0050] A guide pint 54 is inserted into the guide pin insertion
hole 64. The length of the guide pin 54 is larger than that of the
guide pin insertion hole 64. As a result, one end portion of the
guide pin 54 protrudes from a rear end surface (end surface) 60a of
the collar portion 60. As shown in (b) of FIG. 4, a groove 57 is
formed in an outer peripheral surface of one end portion of the
guide pin 54.
[0051] The socket housing 56 is composed of a material identical to
that of the plug housing 6 of the plug-type optical connector 1 and
configured so that can be mated with the plug housing 6. The socket
housing 56 has, between one end 56a and the other end 56b, a
concave portion 68 for a ferrule, which serves to accommodate the
ferrule 53, a concave portion for a spring (concave portion for an
elastic member) 70 that serves to accommodate a compression coil
spring 55, and a concave portion for a pin (concave portion for a
pin) 71 that serves to accommodate one end portion of the guide pin
54.
[0052] The concave portion 68 for a ferrule is formed in one end
portion of the socket housing 56 and, as shown in FIG. 5, has a
size enabling the insertion of one end portion of the plug housing
6 of the plug-type optical connector 1. The concave portion 68 for
a ferrule is open at one end surface of the socket housing 56, and
a plurality (two in the present embodiment) hook portions 78 for a
ferrule are provided in a protruding condition at the inner wall
surface extending between the opening 74 and the bottom surface
76.
[0053] The hook portion 78 for a ferrule has a guide surface 78a
for guiding the ferrule 53 toward the bottom surface 76 of the
concave portion 68 for a ferrule and a locking surface 78b for
locking the ferrule 3 to the concave portion 18 for a ferrule and
can be elastically deformed in the width direction of the socket
housing 56. The guide surface 78a is so inclined as to withdraw
from the base of the hook portion 78 for a ferrule as the bottom
surface 76 (right side in FIG. 4) of the concave portion 68 for a
ferrule is approached. The locking surface 78b faces the bottom
surface 76 of the concave portion 68 for a ferrule and is almost
perpendicular to the installation surface of the hook portion 78
for a ferrule.
[0054] The concave portion 70 for a spring is formed between the
concave portion 68 for a ferrule and the other end 56b of the
socket housing 56 and opened at the bottom surface 76 of the
concave portion 68 for a ferrule. The length from the opening of
the concave portion 70 for a spring to the bottom surface 82 of the
concave portion 70 for a spring is shorter than the natural length
of the compression coil spring 55. The compression coil spring 55
disposed in the concave portion 70 for a spring is abutted by one
end thereof against the rear end surface 60a of the collar portion
60 of the ferrule 53 and abutted by the other end against the
bottom surface 82 of the concave portion 70 for a spring.
[0055] In the socket housing 56, a cable insertion hole 84 is
formed between the concave portion 70 for a spring and the other
end 56b of the socket housing 56. The cable insertion hole 84
serves to insert the optical cable 52 in a linearly extending state
thereof and is opened at the bottom surface 82 of the concave
portion 70 for a spring and at the other end surface of the socket
housing 56.
[0056] The concave portion 71 for a pin is formed between the
concave portion 68 for a ferrule and the other end 56b of the
socket housing 56 and open at the bottom surface 76 of the concave
portion 68 for a ferrule. Two concave portions 71 for a pin are
formed on both sides of the concave portion 70 for a spring.
[0057] As shown in (b) of FIG. 4, a plurality (two in the present
embodiment) hook portions 85 for a pin are provided in a protruding
condition in an open portion of the concave portion 71 for a pin.
The hook portions 85 for a pin are engaged with the groove 57 of
the guide pin 54. In the hook portion 85 for a pin, a surface 85a
positioned on the outside of the concave portion 71 for a pin is an
inclined surface such as to guide one end portion of the guide pin
54 into the concave portion 71 for a pin. On the other hand, a
surface 85b positioned inside the concave portion 71 for a pin is
almost perpendicular to the installation surface of the hook
portion 78 for a ferrule.
[0058] As shown in FIG. 1, an open portion 86 is formed in an upper
wall portion of the socket housing 56. The open portion 86 serves
to insert the cable fixing member 87 and is positioned directly
above the cable insertion hole 84. The cable fixing member 87 has a
configuration similar to that of the cable fixing member 37 in the
plug-type optical connector 1 of the first embodiment. Further,
window portions 88 for locking and receiving that will engage with
the locking hooks 44 of the latch portion 40 provided in the
plug-type optical connector 1 of the first embodiment are provided
in the upper wall portion of the socket housing 56.
[0059] A method for attaching the socket-type optical connector 50
to the optical cable 52 is similar to the method for attaching the
plug-type optical connector 1 of the first embodiment to the
optical cable 2. However, the difference with the first embodiment
is in that the guide pin 54 is attached after the collar portion 60
of the ferrule 53 has been locked by the locking surface 78b of the
hook portion 78 for a ferrule.
[0060] Explaining more specifically, after the collar portion 60 of
the ferrule 53 has been locked by the locking surface 78b of the
hook portion 78 for a ferrule, the guide pin 54 is passed into the
guide pin insertion hole 64 of the body portion 58 in the ferrule
53 and one end portion thereof is caused to protrude from the rear
end surface 60a of the collar portion 60 and introduced into the
concave portion 71 for a pin. As it is introduced therein, the
inclined surface 85a of the hook portion 85 for a pin is pushed by
one end portion of the guide pin 54, whereby the hook portion 85
for a pin is elastically deformed. As a result, the space between
the surface 85a of one hook portion 85 for a pin and the surface
85a of another hook portion 85 for a pin is expanded by the guide
pin 54. At this time, the inclined surface 85a serves to guide one
end portion of the guide pin 54 into the concave portion 71 for a
pin.
[0061] Where the groove 57 of the guide pin 54 reaches the position
corresponding to the hook portion 85 for a pin, the surface 85a of
the hook portion 85 for a pin is released from the push-down state.
As a result, the hook portion 85 for a pin is elastically restored.
The elastically restored hook portion 85 for a pin engages with the
groove 57 of the guide pin 54. Because the surface 85b of the hook
portion 85 for a pin abuts against the circumferential wall surface
of the groove 57 of the guide pin 54, the one end portion of the
guide pin 54 is prevented from being pulled out from the concave
portion 71.
[0062] As described hereinabove, in the socket-type optical
connector 50 of the present embodiment, the concave portion 68 for
a ferrule is formed in the socket housing 56, and the hook portion
78 for a ferrule is provided in the concave portion 68 for a
ferrule. Therefore, similarly to the plug-type optical connector 1
of the first embodiment, no parts have to be prepared separately
for positioning the ferrule 53 and the operation of attaching to
the optical cable 52 can be easily performed.
[0063] Further, in the socket-type optical connector 50 of the
present embodiment, the concave portion 71 for a pin is formed in
the socket housing 56, and a hook portion 85 for a pin is provided
in the open portion of the concave portion 71 for a pin. Because
the hook portion 85 for a pin guides one end portion of the guide
pin 54 into the concave portion 71 for a pin, the one end portion
of the guide pin 54 can be easily introduced into the concave
portion 71 for a pin. Where the groove 57 of the guide pin 54
reaches the position corresponding to the hook portion 85 for a
pin, the hook portion 85 for a pin locks the groove 57. Therefore,
the guide pin 54 can be fixed to the socket housing 56.
[0064] The preferred embodiments of the present invention are
explained hereinabove, but the present invention is not necessarily
limited to these embodiments.
[0065] For example, as shown in FIGS. 1, 2, 5, non-through guide
pin insertion holes 14 are formed in the ferrule 3 of the plug-type
optical connector 1. They may be through holes similarly to the
guide pin insertion holes 64 of the ferrule 53 provided in the
socket-type optical connector 50. In this case, it is preferred
that a concave portion similar to the concave portion for a pin of
the socket housing 56 be also formed in the plug housing 6 and that
the other end portion of the guide pin protruding from the rear end
surface 10a of the collar portion 10 be held in the concave portion
for a pin.
[0066] Further, in the present embodiments, the optical cables 2,
52 are fixed using cable fixing members 37, 87, but the optical
cables 2, 52 may be also inserted into the other end portions of
the plug housing 6 and socket housing 56 and fixed using rubber
booths having insertion holes for inserting the optical cables 2,
52.
* * * * *